Image receptors 2014.ppt

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  • There are different types of x ray films which are classified based on different criteria
  • Wrapper- Wrapper- non absorbent paper or plastic, waterproof, prevent ingress of saliva and light
    Black paper – protect the film from light, damage by fingers and saliva
    Lead foil – prevent residual radiation passing into pt tissues, prevent scatter radiation reaching the film, embossed pattern(wrong placement), rigidity to the packet
    X ray film- rounded corners, embossed dot, convexity towards tube, towards the occlusal surface
  • Image receptors 2014.ppt

    1. 1. Image receptors Priyankesh 1st year post graduate department of oral medicine and radiology
    2. 2. CONTENT  INTRODUCTION  HISTORY  TYPES OF IMAGE RECEPTORS  Radiographic film -direct action film -indirect action film  Digital receptors  Conclusion  references
    3. 3. INTRODUCTION • Image refers to picture or reflection of an object. • Receptor means anything that respond to a stimulus. • IMAGE RECEPTOR - a medium that changes X- ray beam into a visible image.
    4. 4. History  EARLY 1900 – glass plates wrapped in black paper  1913 – hand wrapped cellulose nitrate films  1924 – cellulose triacetate films  1960 – polyester base  1980 – digital radiography ( research and development)  1990 – CCD based imaging  2000 – only digital imaging
    5. 5. FIRST “FILM” GLASS PLATES CELLULOSE NITRATE HIGHLY FLAMMABLE EASILY TORN RESPONSIBLE FOR MANY FIRES IN HOSPITAL BASEMENTS CELLULOSE TRIACETATE
    6. 6. CLASSIFICATION OF X-RAY FILMS • According to packaging 1. Single film packet 2. Double film packet • According to coating of emulsion 1. Single coated 2. Double coated • According to sensitivity 1. Direct action / non-screen film 2. Indirect action / screen film • According to use 1. Intraoral films 2. Extra oral films 3. Duplicating films 4. Self developing film • According to speed of film 1. Slow speed film 2. Fast speed film 3. Hyper speed G
    7. 7. DIRECT/ NON-SCREEN FILM
    8. 8. • Wrapper – non absorbent paper or plastic or soft vinyl - two sides • Tube side – pebbled or smooth surface, usually white • Labeled side – usually two colors
    9. 9.  INFORMATION ON LABELED SIDE:  - name of manufacturer  - number of films enclosed  - raised identification dot  - speed of the film  - statement regarding placement of film
    10. 10. COMPOSITION OF X –RAY FILM
    11. 11. • Base : transparent supporting material upon which emulsion is coated
    12. 12.  Emulsion: Sensitive to X rays and visible light, records the radiographic image. • Film emulsion can be on one side or both sides of base (single emulsion / double emulsion) • Protective overcoat layered on top of emulsion • Emulsion is a gelatin containing the film crystals • Emulsion is the “active” layer of film • Made of mixture of gelatin & silver halide crystals (fluorine, chlorine, bromine, & iodine)
    13. 13. Latent image
    14. 14. • A type of film that is used to make an identical copy of an intraoral or extraoral radiograph. • Used only in darkroom setting • Not exposed to x ray • Emulsion is present on one side of the film • Emulsion side – dull • Non-emulsion side – shiny • Does not have orientation dot • Emulsion side of film must be in contact with radiograph to be duplicated
    15. 15. CASSETTE
    16. 16. CHARGED COUPLE DEVICE  Charge Coupled Devices (CCDs) were invented in October 19, 1969, by William S. Boyle and George
    17. 17. CCD
    18. 18. COMPLEMENTARY METAL OXIDE SEMICONDUCTORS • Silicon-based semiconductors • Electron hole pairs generated in pixels proportional to radiation dose • Each pixel is isolated and directly connected to the transistor • Transferred as a small voltage to transistor • Transistors addressed separately, read by frame grabber • Stored and displayed as a digital gray value
    19. 19. PHOTO STIMULABLE PHOSPHOR PLATES • Photostimulable phosphor plates (PSP) absorb and store energy from x rays and then release this energy as light (phosphorescence) when stimulated by other light of an appropriate wavelength. • photostimulable phosphor material used for radiographic imaging is "Europium-doped" barium fluorohalide..
    20. 20. FLAT PANEL DETECTORS
    21. 21. REFERENCES • Oral radiology- principle and interpretation, -White and pharoah, 5th edition. • Dental radiography, principles and techniques- Haring and jansen – 3rd edition

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